Evaluation of Protection by Caffeic Acid, Chlorogenic Acid, Quercetin and Tannic Acid against the In Vitro Neurotoxicity and In Vivo Lethality of Crotalus durissus terrificus (South American Rattlesnake) Venom.

Systemic envenomation by Crotalus durissus terrificus (South American rattlesnake) can cause coagulopathy, rabdomyolysis, acute kidney injury, and peripheral neuromuscular blockade, the latter resulting in flaccid paralysis. Previous studies have shown that plant products such as tannic acid and theaflavin can protect against the neuromuscular blockade caused by C. d. terrificus venom in vitro. In this work, we used mouse-isolated phrenic nerve-diaphragm preparations to examine the ability of caffeic acid, chlorogenic acid, and quercetin to protect against C. d. terrificus venom-induced neuromuscular blockade in vitro. In addition, the ability of tannic acid to protect against the systemic effects of severe envenomation was assessed in rats. Preincubation of venom with caffeic acid (0.5 mg/mL), chlorogenic acid (1 mg/mL), or quercetin (0.5 mg/mL) failed to protect against venom (10 µg/mL)-induced neuromuscular blockade. In rats, venom (6 mg kg-1, i.p.) caused death in ~8 h, which was prevented by preincubation of venom with tannic acid or the administration of antivenom 2 h post-venom, whereas tannic acid given 2 h post-venom prolonged survival (~18.5 h) but did not prevent death. Tannic acid (in preincubation protocols or given 2 h post-venom) had a variable effect on blood creatinine and urea and blood/urine protein levels and prevented venom-induced leukocytosis. Tannic acid attenuated the histological lesions associated with renal damage in a manner similar to antivenom. The protective effect of tannic acid appeared to be mediated by interaction with venom proteins, as assessed by SDS-PAGE. These findings suggest that tannic acid could be a potentially useful ancillary treatment for envenomation by C. d. terrificus.

Are Silver Nanoparticles Useful for Treating Second-Degree Burns? An Experimental Study in Rats.

Purpose: In this work, the potential usefulness of silver nanoparticles (AgNPs) for treating burn wounds was examined. Methods: Second-degree burns were induced in male Wistar rats by touching the skin with a heated (70°C) metallic device for 10 s, after which the animals were randomly allocated to one of two groups: control (n=8, treated with sterile saline) and experimental (n=8, treated with AgNPs, 0.081 mg/mL; 50 µL applied to the burn surface). Seven, 14, 21 and 28 days after lesion induction two rats from each group were killed and blood samples were collected for a complete blood count and to assess oxidative stress. The livers were examined macroscopically and skin samples were collected for histological analysis. Results: Macroscopically, wound healing and skin remodeling in the experimental group were similar to the saline-treated rats. Likewise, there were no significant differences in the histological parameters between the two groups. However, treatment with AgNPs caused a persistent reduction in white blood cell (WBC) counts throughout the experiment, whereas platelet counts increased on days 7 and 28 but decreased on days 14 and 21; there was also an increase in the blood concentration of reduced glutathione on day 7 followed by a decrease on days 21 and 28. There were no significant changes in blood glutathione peroxidase (GSH-Px) and catalase (CAT) activities or in the serum concentration of thiobarbituric acid reactive substances. Conclusion: The findings of this study raise questions about the potential transitory effects of AgNPs based on the changes in WBC and platelet counts, blood glutathione concentrations and macroscopic hepatic alterations.

Acute kidney injury caused by the intraperitoneal injection of Bothrops jararaca venom in rats.

We examined the ability of Bothrops jararaca venom (12.5 mg/kg) injected intraperitoneally (i.p.) to cause acute kidney injury (AKI) in rats. Blood urea and creatinine (AKI biomarkers, in g dL-1) were elevated after 2 h in venom-treated rats (urea: from 0.41 ± 0.1 to 0.7 ± 0.03; creatinine from 46.7 ± 3.1 to 85 ± 6.7; p < 0.05; n = 3 each), with no change in circulating reduced glutathione. Venom-treated rats survived for ∼6 h, at which point platelets were reduced (×103 µL-1; from 763.8 ± 30.2 to 52.5 ± 18.2) whereas leukocytes and erythrocytes were slightly increased (from 4.7 ± 0.3 to 6.6 ± 0.1 × 103 µL-1 and from 8.38 ± 0.1 to 9.2 ± 0.09 × 106 µL-1, respectively; p < 0.05); blood protein (5.2 ± 0.4 g dL-1) and albumin (2.7 ± 0.1 g dL-1) were normal, whereas blood and urinary urea and creatinine were increased. All parameters returned to normal with antivenom given 2 h post-envenomation. The i.p. injection of venom caused AKI similar to that seen with other routes of administration.

Experimental model for removal of snake venom via hemoperfusion in rats.

OBJECTIVE: To examine the efficiency of hemoperfusion in removing South American rattlesnake (Crotalus durissus terrificus) venom from rats compared with neutralization by antivenom. DESIGN: An exploratory experimental investigation in rats involving the injection of snake venom with or without subsequent hemoperfusion or antivenom administration. SETTING: Basic animal research laboratory in a private university. ANIMALS: Normal, healthy male Wistar rats (0.29-0.40 kg, 3-6 months old) from a commercial breeder. INTERVENTIONS: Four experimental groups of randomly allocated rats (n = 3/group) were studied: Group 1: rats were injected with a single dose of venom (5 mg/kg, IM, in the right thigh) with no other treatment; blood samples were collected minutes before death to determine leukocyte, platelet, and erythrocyte counts; Group 2 (Control): rats underwent hemoperfusion alone for 60 min using a hemoperfusion cartridge designed for protein adsorption (by granulated charcoal) and protein precipitation (by tannic acid); Group 3 (Venom + antivenom): rats were injected with venom (5 mg/kg, IM) and, 10 min later, were treated with antivenom at the venom:antivenom ratio recommended by the manufacturer; Group 4 (Venom + hemoperfusion): Rats were injected with venom (5 mg/kg, IM) and, 10 min later, were hemoperfused for 60 min. In groups 2-4, blood samples were collected for leukocyte, platelet, and erythrocyte counts 24 h after venom. MEASUREMENTS AND MAIN RESULTS: Rats injected with venom alone (Group 1) developed signs of neurotoxicity and ataxia and died in 9.0 ± 0.43 h but showed no changes in leukocyte or erythrocyte counts. In contrast, there were no deaths in groups 2-4. The lack of deaths in Groups 3 and 4 indicated that antivenom and hemoperfusion, respectively, protected against the lethal effects of the venom. CONCLUSIONS: Hemoperfusion with a double-action hemoperfusion cartridge capable of protein adsorption and precipitation protected rats against C. d. terrificus venom.

Oxidative stress and changes in hematological and biochemical biomarkers in Crotalus durissus terrificus (South American rattlesnake) venom-induced acute kidney injury in rats / Estrés oxidativo y alteraciones en biomarcadores hematológicos y bioquímicos en lesión renal aguda inducida por el veneno de Crotalus durissus terrificus (cascabel de America del Sur) en ratones

Abstract Acute kidney injury (AKI) is the major cause of mortality following bites by the South American rattlesnake Crotalus durissus terrificus. We investigated the early onset of Crotalus durissus terrificus venom-induced AKI in rats within 2 h of venom injection and its attenuation by antivenom. Several biomarkers were used to monitor AKI in the absence or presence of antivenom. Male Wistar rats were divided into five groups (n=5 each): G1, rats injected with saline (control); G2, rats injected with venom (6 mg kg-1, intraperitoneally) and euthanized after 2 h to evaluate AKI; G3 and G4, rats injected with 0.9% sterile saline or antivenom 2 h after venom, respectively, and monitored until death or up to 24 h post-venom, and G5, rats injected with antivenom alone and monitored for 24 h. Blood, urine and renal tissue samples were collected immediately after death to assess oxidative stress, hematological and biochemical alterations, and renal histological damage. Venom caused AKI within 2 h (G2) that persisted for up to 8.2 ± 1.6 h (G3), as confirmed by increases in blood urea, creatinine, and renal proteinuria; these increases were attenuated by antivenom. There were no changes in blood protein concentrations in G2 and G3, whereas there were increases in blood reduced glutathione, glutathione peroxidase, and plasma TBARS (but not in catalase) that were attenuated to varying extents by antivenom. There were no marked changes in platelets or leukocytes, but an increase in erythrocytes after 8.2 h with venom alone was attenuated by antivenom. Renal glomerular and tubular damage was greatest after 2 h post-venom groups alone was attenuated by antivenom. Renal glomerular and tubular damage was greatest after 2 h post-venom and declined thereafter. Venom caused early-onset AKI, with variable effects on lipid peroxidation and oxidative stress. Antivenom attenuated the AKI, as shown by the decrease in blood urea and the normalization of proteinuria, without protecting against lipid peroxidation.

Resumen La injuria o lesión renal aguda (LRA) es la mayor causa de mortalidad debido a las mordeduras por cascabeles Crotalus durissus terrificus. Se estudió la instalación precoz de LRA, en ratas, inducida por el veneno de Crotalus durissus terrificus después de 2 h de su inoculación y la atenuación por el antiveneno. Se utilizaron diversos biomarcadores para monitorear LRA en ausencia o presencia del antiveneno. Ratas Wistar machos fueron divididos en 5 grupos (n=5 por grupo): G1, ratas inoculadas con solución salina (control); G2, ratas inoculadas con veneno (6 mg kg-1 dosis, vía intraperitoneal), y sacrificadas después de 2 h para evaluar LRA; G3 y G4, ratas inoculadas con 0.9% de solución salina esterilizada o antiveneno luego de 2 h después de inoculado el veneno, respectivamente, y monitoreadas hasta su muerte o hasta 24 h después de inoculado el veneno; y G5, ratas inoculadas con antiveneno solo y monitoreadas durante 24 h. Las muestras de sangre, orina, y tejido renal fueron colectadas inmediatamente después de la muerte de los animales para evaluar estrés oxidativo, alteraciones hematológicas y bioquímicas, y daño histológico renal. El veneno causó LRA dentro de las 2 h (G2) persistiendo durante más de 8,2 ± 1,6 h (G3), estando esto confirmado por el incremento de urea sanguínea, creatinina, y proteinuria renal; estos aumentos disminuyeron con la aplicación del antiveneno. No se observaron alteraciones en las concentraciones de proteínas sanguíneas en G2 y G3, mientras que se encontraron incrementos en glutatión reducido sanguíneo, glutatión peroxidasa y TBARS plasmática (pero no en catalasa), que disminuyeron con la aplicación del antiveneno aunque en diferente grado. No ocurrieron alteraciones marcadas de plaquetas o leucocitos, mientras que el aumento de glóbulos rojos observado luego de 8,2 h de la inoculación con veneno, disminuyó con el antiveneno. El daño renal glomerular y tubular fue más importante luego de 2 h de la inoculación con veneno y posteriormente disminuyó. El veneno causó LRA precoz a las 2 h, con efectos variables sobre la peroxidación lipídica y el estrés oxidativo. El antiveneno redujo el daño renal, conforme lo demostrado por la disminución en la urea sanguínea y por la normalización de la proteinuria, aunque no se observó protección contra la peroxidación lipídica.